Cough syrup has long been a contentious elixir — usually because of its hallucinogenic properties and frequent abuse, particularly among teens. This week, it’s making headlines again, tragically: tainted medicine is believed to be responsible for more than a dozen deaths in Pakistan.

At least 16 people have died in the city of Lahore, located in the northeast region of the country near the Indian border, after drinking what police call toxic cough syrup. Another six have been hospitalized, with two in critical condition, the New York Times reports. The syrup was sold under the name Tyno, local police told the Times, and all the victims whose lives it claimed were between the ages of 20 and 45. Police have launched a homicide investigation involving the factory where the syrup came from.

In the meantime, three pharmacies have been shut down and their owners have been arrested, according to Agence France Presse. The provincial health authority has called for the confiscation of the syrup from any remaining pharmacies. Officials have sent samples to a laboratory and await detailed analysis.

So far, all deaths have occurred in the city’s low-income suburb of Shahdra. Local police station chief Atif Zulfiqar told AFP that many of the victims were addicts who appeared to have taken the syrup to get high. Some were found dead in a graveyard commonly used for taking drugs, while others died in the hospital. A few have been discharged after receiving successful treatment.

The spate of deaths comes less than a year after more than 100 patients died from contaminated heart medicine — also in Lahore, Pakistan’s second-largest city after Karachi. In that incident, many of the victims were poor patients who had received the drug for free.